Process for stabilizing fatty oil polymers



I Patented May 30, 1939 UNITED STATES PATENT. OFFICE $160,512 raocsssroa smnmzmo mm on. mamas No Drawing. Application April 27, 1937, Serial5 Claims.

fluoride as disclosed in my copending application,

Serial No. 85,332, filed June 15, 1936, are used in combination withmineral lubricating oils for lubrication purposes. As I have shownin-my,

copending application, these polymers are miscible with minerallubricating oils in all proportions, if a certain characteristic of thepolymers,

the viscosity raising coeflicient, is kept below certain limits. Theviscosity raising coeflicient is expressed by the formula log V -log VX29.54

in" which Vs: is the viscosity at C. in Saybolt seconds of a 6% byweight solution of the polymer in a mineral lubricating oil and VA isthe viscosity at 50 C. in the same units of the mineral oil itse L11.ting oils of relatively high aromaticity are miscible with polymershaving viscosity raising coefficients up to about 2, while highlyparaflinic oils, i. e., those which possess viscosity indexes of about100 or higher, are only capable of dissolving polymers of viscosityraising coefficients not in excess of about .9 or 1.

Viscosity raising coeificients of polymers obviously will vary depending-upon how far the polymerization has progressed. This in turn iscontrolled by the degree of unsaturation of the fatty oils, the type ofcatalysts used, and the time and temperature of the polymerizationtreatments. As has been shown, from the point of view of lubrication,the most desirable polymers have viscosity raising coefficients aboveabout .5. Likewise, it is not desirable that the polymers containunpolymerized fatty oils.

The manufacture of the most suitable polymers is commonly carried out bydigesting a moderately-drying or semi-drying fatty oil with theproperamount of catalyst such as boron fluoride at moderately elevatedtemperatures for a period which may last several days. When thepolymerization has reached the desired point, the mixture may bedissolved in a suitable solventrsuch as ben'zol, and the resultingsolution is washed with an aqueous polar organic solvent such as a loweralcohol or ketone, for instance methyl, ethyl, or

In the Netherlands May 9, 1936 propyl alcohol, acetone, methyl-ethylketone, etc., containing small amounts of water, whereby the boronfluoride catalyst is hydrolyzed, and the reaction is terminated: Thesolvent is then removed by distillation, and the polymer, which is anextremely viscous mass, may tie-dissolved in a mineral lubricating oilin the proportion necessary, to produce a finished lubricating oil ofimproved oiliness, which proportion usually varies between about 2-'6%by weight of the oil. Usually, however, the polymer goes first tostorage, to be blended with mineral lubricating oils at some laterconvenient time.

- It has been found that the polymers in storage undergo certain highlyundesirable changes. A slow after-polymerization takes place, whichcauses a more or less rapid decline in the :Tolubility, of at least aportion of the polymers in mineral lubricating oils, particularly inthose of high viscosity indexes. This after-polymerization may progressto a point at which the polymers or part thereof have becomesubstanwhich the polymer comes in contact, as the additionofanti-oxidants has no retarding effect,

and polymerization catalysts other than air are not normally present.Polymers produced by catalytic polymerization of unsaturated fatty oilsseem to differ in this respect from polymers produced by electricalpolymerization of fatty oils by means of silent electric discharges. Thelatter products appear to be essentially saturated and do not undergoafter-polymerization upon storage. I

It is the purpose of this invention to provide a simple means forstabilizing polymers from fatty oils of the type herein describedwithout otherwise lowering their value for blending purposes for theproduction of high-grade mineral lubricating oils of improved oiliness.

I have discovered that the after-polymerization hereinbefore describedcan be stopped effectively by incorporating into the polymers a smallamount of a mineral lubricating oil or'grease. Frequently about 5% ofmineral lubricating oil by volume is sumcientalthough, in generaL'and inorder to be on the-safe side, I prefer to add larger quantities, forinstance 30 to 300%.

While there is no reasonfrom the point of stability to add even largerquantities, it is generally advantageous to limit the quantity ofmineral oil the polymers, the improvement in stability being very rapidupon the addition of the first few per cent of mineral oil, and themagnitude of the improvement declining upon further addition to reachapproximately zero, after having added about 300%. Furthermore, it maynot be desirable to have excessively large amounts of the stabilizingoil in the lubricating oil with which the polymer is eventually blendedto produce a finished lubricating oil of a certain grade. Also theadmixture of relatively large amounts of mineral oil calls for extrastorage capacity for the polymers, which contributes to the cost of theproduct; and if the polymer is to be shipped over long distances to beblended with a mineral oil at seine other location, the cost oftransportation is raised in proportion to the amount of mineral oilcontained in the polymer.

On the other hand relatively large quantities of stabilizing oil of theorder of to 300% sufficiently reduce the viscosity of the polymer sothat it can be handled by ordinary equipment available in refineries, i.e., it can be pumpedby pumps designed to handle lubricating oils and thelike, whereas prior to dilution the extreme I viscosity of the polymermakes handling a very difficult problem.

Thus depending upon conditions of handling, storage, shipment, etc., Iusually dilute the polymer in the above indicated proportions andpreferably with about to 150% of a mineral oil, immediately after havingcompleted the manufacture of the polymer. This dilution may be carriedout before or after the removal of the catalyst from the polymer.Generally it is easier to do the blending while the polymer is hot or isin solution of a low viscosity solvent as benzol, and the steps ofwashing and distilling of the solvent may be carried out in the presenceof the stabilizing oil, if desired. Under some circumstances thepolymerization itself may be carried out in the presence of a relativelysmall amount of mineral lubricating oil.

fore if the viscosity raising coeflicient of the polymer is betweenabout 1 and 2, a lubricating oil of relatively high aromaticity, i. e.,having a vis- -cosity index substantially below 100; must be used forstabilization, whereas if this constant is below 1, all lubricating oilsare suitable includin oils having high viscosity indexes of the order ofI l 100 and above.

The following examples illustrate the effect of adding stabilizing oilsto fatty oil polymers.

Example I Soya bean oil was digested at 70 C. for 50 hours with 2% byweight of boron fluoride. The

resulting polymer was washed several times with 96% ethyl alcohol at 25C. while centrifuging,

to remove the catalyst. The alcohol retained by v the polymers wasremoved from the latter by distillation.

The polymer, free from catalyst, was then divided into two portions, oneof which was blended with an equal volume of lubricating oil. Bothportions, the blended and the unblended, were subjected to storagetests. After a few days the unblended portion showed considerableflocculation,'and after about two months a gelatinous mass hadseparated, particularly'on the surface of the sample, while the blendedportion showed no. change at all during the entire period.

The unblended portion had become practically insoluble in minerallubricating oils, particularly in those of high paraflinicity such asPennsylvania oils, solvent extracted oils, synthetic lubricating oils ofthe type produced by polymerization of olefines obtained in the vaporphase cracking of paraflin wax.

Example II tions, and one portion while still hot was mixed withone-half of its own volume of a lubricating oil. Both portions werestored for several months. The blended. portion showed no visiblechanges, while the unblended portion had become highly gelatinizedandalmost completely insoluble in mineral oils of high viscosity indexes.

Example III A mixture of 85% of rapeseed oil and 15% of cotton seed oilwas digested at 80 C. for 80 hours with 1% by weight of boron flubride.The polymer so obtained was washed 4 times with 96% ethyl alcohol at 50C., and the washed polymer was strippedof dissolved alcohol bydistillation. The finished product was divided into two portions, one ofwhich was immediately diluted with twice its own volume of a lubricatingoil. After a few days the undiluted portion began showing signs offlocculation and gelatinization, which rapidly progressed upon continuedstorage, while the diluted portion remained unchanged over the entirestorage period of several months.

I claim as my invention:

1. In the process of producing a storage stable concentrate of apolymerized fatty oil obtained by catalytic polymerization of anunsaturated polymerizable fatty oil, the steps of digesting saidpolymerizable fatty oil with a polymerization catalyst under conditionsto produce a polymer which is miscible with mineral lubricating oils insubstantially all proportions, diluting the resulting polymer with 5 to300 volume per cent of a mineral lubricating oil and separating thecatalyst from the resulting solution.

2. A storage stable polymer concentrate consisting essentially of asolution of fatty oil polymer which is miscible with mineral lubricatingoil in substantially all proportions and which in the absence ofpolymerization catalysts under-- sisting essentially of a solution of acatalytically 7 produced polymer of an unsaturated vfatty oil having aviscosity raising coeflicient not in excess of 2, m 5 to 300 volume percent of a mineral lubricating oil miscible with said polymer insubstantially all proportions.

5. A storage stable polymer concentrate consisting essentially of asolution of a catalytically produced polymer of a semi-drying iatty oilhaving a. viscosity raising coeflicient between about .5 to 2.0, in 5 to300 volume per cent of a mineral lubricating oil miscible therewith insubstantially all proportions.

' EGON EICHWALD.

